The purpose of this study is to see if antibody (Ab) to AFP can be identified in human placentas including those from patients with toxemia. So far we have tentative evidence that such complexes are present in, at least, one placenta from a patient with toxemia. AFP seems to be an immunosuppressive compound and the human host appears to be tolerant of its presence during both gestation and malignancies such as carcinoma of the liver. Whether it is responsible for human tolerance to the placenta as well as to certain malignancies is not known. However, perturbations in the host response to this compound may be relevant not only to normal pregnancies but to certain tumors as well.